also, bite tongue
- to keep quiet when one would rather speak
- used when telling people not to speak
- When she said that she was very hardworking I had to hold my tongue.
- I often have to hold my tongue when he tells me how good he is at football. I know that he can hardly kick.
- You better hold your tongue while we are in the museum, young man!
- You need to hold your tongue while the principal is talking during assemble today.
- I had to hold my tongue in order to keep the peace at our family gathering.
The idiom is a synonym of "bite your tongue" which has the same meaning. It is often used after someone has said something instead of before.
In the case of "hold your tongue" the word hold is used in place of refrain. To refrain means to keep from doing something. So, if you refrain your tongue you keep it from doing something. It is also meant to keep your peace. As used in the traditional wedding vows: "speak now or forever hold your peace."
The Tale of Melibus (c. 1387): "Thee is better hold thy tongue still, than for to speak."